Update WIT world to WASI P3 RC

[itowlson]

This is my best guess at what our world looks like with the Wasmtime 37 update. It's been a long time since we updated the core platform WASI reference so I'm not super confident but I think wasi:cli/imports and wasi:http/handler are all we need. I'm not quite sure if we need a 3.5 world that exports HTTP P2: apps targeting spin:[email protected] will be fine but I'm not sure if an app using the P2 handler signature could target spin:[email protected] (and work by inclusion of the 0.2.0 deps), or whether it would need to (since presumably such an app would be using P2 imports as well???). So @fibonacci1729 @dicej if you could take a critical look that would be super helpful... thanks!

[dicej]

@itowlson regarding your questions and concerns about which interfaces to include in which worlds, etc.: I think what you've done here is sufficient; if we find we need more worlds and/or a different selection of interfaces in a given world, we can add those. Meanwhile, an SDK can always define their own world(s) corresponding to a unique subset of the interfaces Spin 3.5.x supports, according to what that SDK provides bindings for; i.e. they need not be restricted to one of the worlds defined here.